Production of bioenergy in post-mining landscapes in Lusatia -: Perspectives and challenges for alternative landuse systems

Since the German reunification in 1990, lignite production in the Lusatian mining district has significantly decreased as a result of substantial economic and structural changes. This development coincides with efforts by the government of the stare of Brandenburg to enhance the production of biomass on set-aside arable and mining land for energy transformation purposes. In this context the goal is that a share of 3% of the primary energy consumption should come from biomass. As part of the on-going recultivation activities in the post-mining landscapes, short-rotation tree plantations as a special form of energy forests have recently come into focus. Thus, in 1995 a 2.5 ha short-rotation plantation was established on clayed-sandy, nutrient-poor substrates in the Lusatian mining area Welzow-Sud in order to study the ecological potential of fast-growing tree species under the prevailing site conditions. Even under unfavourable soil conditions with a low N and P supply, above-ground biomass production ranged from 2.5 to 11.7 tons dry matter per hectare. Three-year-old plants of fast growing tree species like poplar, willow, and aspen were marked by low mean N (5.3 mg g(-1)), Cl (113 mug g(-1)), Cl (0.8 mug(-1)) and Pb (0.5 mug g(-1)) contents. Therefore, this material is a most favourable biofuel. For the biomass accumulated within this 3-year period a calorific value of 30 000 MJ ha(-1) a(-1) has been calculated. The ash content of 2.4% allows this material to be used for amelioration purposes. This recycling approach guarantees balanced phosphorus, calcium, and magnesium supply. To maintain adequate site productivity only for nitrogen and potassium, a compensatory fertilization is required. (C) 2000 Elsevier Science B.V. All rights reserved.